<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Frameset//EN">
<?php 
$edno = "";
$dve = "";
$oper = "";
$result = "";

	if(isset($_POST["submit"])) {
		$edno = $_POST['edno'];
		$dve = $_POST['dve'];
		$oper = $_POST['operation'];
		$result = 0;
		
		if($oper == '+') {
			$result = $edno + $dve;
		}
	}
?>
<html>
<head>
<title>Exercise 1</title>
</head>
<body>
    <form method="post" action="exersice1.php">
    	<p>	    	
	    	<input type="text" name="edno" value="<?php echo $edno;?>"/>	    		    	
	    	<select name="operation">
	    		<option value="+">+</option>
	    		<option value="-">-</option>
	    		<option value="*">*</option>
	    		<option value="/">/</option>
	    	</select>	    	
	    	<input type="text" name="dve" value="<?php echo $dve;?>"/>
	    	<input type="submit" value="Calculate" name="submit">
    	</p>
    	<p>Result: <input value="<?php echo $result;?>"/></p>
    </form>		
</body>
</html>